/**
 * 判断手指触摸位置
 */
export function determineDirection(clipX, clipY, clipWidth, clipHeight, currentX, currentY) {
  /*
   * (右下>>1 右上>>2 左上>>3 左下>>4)
   */
  let corner;
  /**
   * 思路：（利用直角坐标系）
   *  1.找出裁剪框中心点
   *  2.如点击坐标在上方点与左方点区域内，则点击为左上角
   *  3.如点击坐标在下方点与右方点区域内，则点击为右下角
   *  4.其他角同理
   */
  const mainPoint = [clipX + clipWidth / 2, clipY + clipHeight / 2]; // 中心点
  const currentPoint = [currentX, currentY]; // 触摸点

  if (currentPoint[0] <= mainPoint[0] && currentPoint[1] <= mainPoint[1]) {
    corner = 3; // 左上
  } else if (currentPoint[0] >= mainPoint[0] && currentPoint[1] <= mainPoint[1]) {
    corner = 2; // 右上
  } else if (currentPoint[0] <= mainPoint[0] && currentPoint[1] >= mainPoint[1]) {
    corner = 4; // 左下
  } else if (currentPoint[0] >= mainPoint[0] && currentPoint[1] >= mainPoint[1]) {
    corner = 1; // 右下
  }

  return corner;
}

/**
 * 图片边缘检测检测时，计算图片偏移量
 */
export function calcImageOffset(data, scale) {
  let left = data.imageLeft;
  let top = data.imageTop;
  scale = scale || data.scale;

  let imageWidth = data.imageWidth;
  let imageHeight = data.imageHeight;
  if ((data.angle / 90) % 2) { //翻转90°
    imageWidth = data.imageHeight;
    imageHeight = data.imageWidth;
  }
  const {
    clipX,
    clipWidth,
    clipY,
    clipHeight
  } = data;

  // 当前图片宽度/高度
  const currentImageSize = (size) => (size * scale) / 2;
  const currentImageWidth = currentImageSize(imageWidth);
  const currentImageHeight = currentImageSize(imageHeight);

  left = clipX + currentImageWidth >= left ? left : clipX + currentImageWidth;
  left = clipX + clipWidth - currentImageWidth <= left ? left : clipX + clipWidth - currentImageWidth;
  top = clipY + currentImageHeight >= top ? top : clipY + currentImageHeight;
  top = clipY + clipHeight - currentImageHeight <= top ? top : clipY + clipHeight - currentImageHeight;
  return {
    left,
    top,
    scale
  };
}

/**
 * 图片边缘检测时，计算图片缩放比例
 */
export function calcImageScale(data, scale) {
  scale = scale || data.scale;
  let {
    imageWidth,
    imageHeight,
    clipWidth,
    clipHeight,
    angle
  } = data
  if ((angle / 90) % 2) {
    [imageWidth, imageHeight] = [imageHeight, imageWidth]
  }
  if (angle !== 0 && scale == Math.max(clipWidth / imageHeight, clipHeight / imageWidth)) {
    return Math.max(clipWidth / imageWidth, clipHeight / imageHeight)
  }
  if (imageWidth * scale < clipWidth) {
    scale = clipWidth / imageWidth;
  }
  if (imageHeight * scale < clipHeight) {
    scale = Math.max(scale, clipHeight / imageHeight);
  }
  return scale
}

/**
 * 计算图片尺寸
 */
export function calcImageSize(width, height, data) {
  let imageWidth = width,
    imageHeight = height;
  let {
    clipWidth,
    clipHeight,
    sysinfo,
    width: originWidth,
    height: originHeight
  } = data
  const cw = clipWidth || originWidth
  const ch = clipHeight || originHeight
  if (imageWidth && imageHeight) {
    if (imageWidth / imageHeight > cw / ch) {
      imageHeight = clipHeight || originHeight;
      imageWidth = (width / height) * imageHeight;
    } else {
      imageWidth = cw;
      imageHeight = (height / width) * imageWidth;
    }
  } else {
    let sys = sysinfo || uni.getSystemInfoSync();
    imageWidth = sys.windowWidth;
    imageHeight = 0;
  }
  return {
    imageWidth,
    imageHeight
  };
}

/**
 * 勾股定理求斜边
 */
export function calcPythagoreanTheorem(width, height) {
  return Math.sqrt(Math.pow(width, 2) + Math.pow(height, 2));
}

/**
 * 拖动裁剪框时计算
 */
export function clipTouchMoveOfCalculate(data, event) {
  const clientX = event.touches[0].clientX;
  const clientY = event.touches[0].clientY;

  let {
    clipWidth,
    clipHeight,
    clipY: oldClipY,
    clipX: oldClipX,
    clipStart,
    isLockRatio,
    maxWidth,
    minWidth,
    maxHeight,
    minHeight
  } = data;
  maxWidth = uni.upx2px(maxWidth) // maxWidth / 2;
  minWidth = uni.upx2px(minWidth) // minWidth / 2;
  minHeight = uni.upx2px(minHeight) // minHeight / 2;
  maxHeight = uni.upx2px(maxHeight) // maxHeight / 2;

  let width = clipWidth,
    height = clipHeight,
    clipY = oldClipY,
    clipX = oldClipX,
    // 获取裁剪框实际宽度/高度
    // 如果大于最大值则使用最大值
    // 如果小于最小值则使用最小值
    sizecorrect = () => {
      width = width <= maxWidth ? (width >= minWidth ? width : minWidth) : maxWidth;
      height = height <= maxHeight ? (height >= minHeight ? height : minHeight) : maxHeight;
    },
    sizeinspect = () => {

      if ((width > maxWidth || width < minWidth || height > maxHeight || height < minHeight) && isLockRatio) {
        sizecorrect();
        return false;
      } else {
        sizecorrect();
        return true;
      }
    };
  //if (clipStart.corner) {
  height = clipStart.height + (clipStart.corner > 1 && clipStart.corner < 4 ? 1 : -1) * (clipStart.y - clientY);
  //}
  switch (clipStart.corner) {
    case 1:
      width = clipStart.width - clipStart.x + clientX;
      if (isLockRatio) {
        height = width / (clipWidth / clipHeight);
      }
      if (!sizeinspect()) return;
      break;
    case 2:
      width = clipStart.width - clipStart.x + clientX;
      if (isLockRatio) {
        height = width / (clipWidth / clipHeight);
      }
      if (!sizeinspect()) {
        return;
      } else {
        clipY = clipStart.clipY - (height - clipStart.height);
      }

      break;
    case 3:
      width = clipStart.width + clipStart.x - clientX;
      if (isLockRatio) {
        height = width / (clipWidth / clipHeight);
      }
      if (!sizeinspect()) {
        return;
      } else {
        clipY = clipStart.clipY - (height - clipStart.height);
        clipX = clipStart.clipX - (width - clipStart.width);
      }

      break;
    case 4:
      width = clipStart.width + clipStart.x - clientX;
      if (isLockRatio) {
        height = width / (clipWidth / clipHeight);
      }
      if (!sizeinspect()) {
        return;
      } else {
        clipX = clipStart.clipX - (width - clipStart.width);
      }
      break;
    default:
      break;
  }
  return {
    width,
    height,
    clipX,
    clipY
  };
}

/**
 * 单指拖动图片计算偏移
 */
export function imageTouchMoveOfCalcOffset(data, clientXForLeft, clientYForLeft) {
  return {
    left: clientXForLeft - data.touchRelative[0].x,
    top: clientYForLeft - data.touchRelative[0].y
  };
}